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Re: Crocodilian vs Avian looks




On Thu, 8 Feb 2001, David Marjanovic wrote:

> 
> Due respect to Mr. Witmer (and his works on cranial pneumaticity), but the
> restoration of a protoceratopsian without cheeks looks very awkward, because
> these animals chewed and would have needed to prevent the food from falling
> out. I can't buy it. I wouldn't expect exact identity to mammalian cheeks
> (and lips) anyway, because we're talking of convergences...
> 

I would have to agree here. Although the EPB does suggest that cheeks
were not present in the common dinosaur ancestor there are good
functional reasons that they may have evolved. I can't imagine the
hadrosaur or ceratopsian dental battery working efficiently without
cheeks I will admit that the previous osteological correlates that have
been used, such as buccal emargination aren't as solid as we previously
believed but the fact that ankylosaurs (eg. Panoplosaurus) develop
thumping great osteoderms that
cover the emargination is fairly strong evidence that the area was
covered by a sheet of skin (ie. a cheek).

cheers

Adam Yates